Pavegeno928

What is the average gas mileage you get in your 911?

Over the last three years I have owned my car I average about 14 mpg in the city and about 21 on the highway using 93 octane. I live on the coast where it is completely flat. I drive fairly conservatively though I will redline it occasionally once it is warmed up.

If you think this mileage is low, what typically causes low mileage other than a heavy right foot?

Thanks,

Geno

Ed Hughes

That sounds pretty low for around town. I've got a chip, cams and headers that sound ever-so-good (meaning lots of heavy footed driving) and I get closer to 16 or 17 around town, maybe down to 15 on a long backroads trip. Highway I'm close to 20 if I'm lucky, but I don't get a lot of freeway miles in.

rusnak

Wow. I used to get upwards of 30 on the highway, depending on temperature and traffic. My 911 is totally bone stock. If I set the cruise control for 80 and head out to the coast, I might get around 32 mpg. That has dropped recently, but I haven't checked it since I went through the fuel injection and replaced a bunch of stuff. Also I suspect the newer gas has caused mileage to suffer.

I know the 911SC gets worse mileage than the 3.2. The SC gets around 24 highway, while the 3.2 gets around 30 like I said. I don't know what it gets around town since it takes a lot of miles to compute consumption.

ron mcatee

I get around 27 in my 88 Carrera. You may need the CO checked to insure it's not too lean.

Pavegeno928

I'm replacing the oxygen sensor this weekend and will ask some questions about the mixture.

Anything else to look for?

911vet

24 mpg spirited driving curvy hill roads
9 mpg on the track

rusnak

Do you have access to an LM1 or other type of air fuel gauge?

My fuel mileage dropped to the mid to high 20s, and when I installed the cat bypass, I found that it was running so rich at idle, that it made my eyes water. That was the beginning of my air fuel adjustment journey.

Amber Gramps

and this is exacly why my cat is going to stay on now that it is back on....

I'm going to say O2 sensor. go with a real factory unit, not a splice to fit

and my '88's milage is way up at the 30mpg range 'cause I use that redneck high test blend to go with my chip.

rusnak

I meant to say that first my 911 gas mileage had dropped to around 25-27 mpg. I had no idea why. Later, because of fuel injection problems, I got a new catalytic converter. While waiting for it to arrive, I bought a cat bypass and installed it. Without the cat, the exhaust smell was something awful. It made my eyes water, and it was embarrasing sitting in traffic. It was way rich. When I re-installed the cat, of course it masks all the smell.

I have not re-checked the mileage, so I don't know if it's improved now that I have the idle and CO level adjusted. I changed the injectors, intake boot, fuel pump, AFM, and even the DME brain. I did check the afr going down the freeway, and it fluctuates between .97 and 1.03 Lambda, so I think everything is working ok.

I should check the fuel mileage to see if in fact the newer gas has caused mileage to suffer. When I say I was getting 30+ mpg, I am talking about 2002 or so when I last checked mileage.

I wonder if higher octane fuel gets better mileage? It seems like it would be possible.

rnln

I get around 21-23 over all, 80% freeway.

jwilson95

22 in mixed driving, 20 if I'm getting on it, 25+ on cruises

theiceman

i get 17mpg on my SC mostly highway

but it's a Porsche ..... is gas millage REALLY that important ?

not to me ....

jwilson95

That's what I thought initially too, but I have a company car I use for DD!

theiceman

actually me too ......

and as far as company cars go the 2009 Maxima with free gas isn't a bad one to have ...

rusnak

anything with free gas is fine with me.